This invention relates to directional control of fluids discharged from nozzles. More particularly, this invention relates to directional control of exhaust fluids discharged from a jet propulsion engine and consequently to directional control of jet engine thrust used to move vehicles of all types.
In many situations, it is desirable or necessary to directionally control the thrust supplied by a jet propulsion engine. For example, the well known thrust reversers of a jet propelled airplane redirect the exhaust fluid of the jet propulsion engines to slow down or effectively brake the airplane upon landing. Other types of control over the direction of the fluid stream supplying thrust to a jet airplane are also advantageous during both on ground and in flight procedures. During both in flight and on ground conditions, it is often advantageous to reduce the thrust without reducing the power setting of the engine. For example, during the ground taxi operation, the most advantageous engine power from the standpoint of other airplane system requirements may be inconsistent with the need for low thrust to prevent the airplane from travelling too fast. Similarly on the landing approach, the low engine speed necessary to obtain the proper approach speed and the typical delay in thrust build up that occurs when the engine power setting is advanced, often makes it difficult to accelerate the airplane for go around or emergency flight procedures. Reduction of the forward thrust component by re-directing the exhausted fluid stream to provide low forward thrust while maintaining engine speed is often termed thrust spoilage or thrust modulation. Another advantageous type of directional control over the thrust produced by a jet airplane engine is generally known as thrust vectoring. Normally, thrust vectoring apparatus permits the direction of thrust to be controlled with respect to the vertical axis. Thus, thrust vectoring can be used to shorten take-off distance or can be used for in flight maneuvering.
Although the above described aspects of controlling the direction of thrust supplied by a jet engine have been discussed in the context of jet airplanes, it will be recognized that similar requirements exist with respect to other types of vehicles propelled by jet engines, whether such vehicles travel on the ground or on or below the surface of water. Such jet propulsion engines may exhaust gases, liquids, or a combination thereof.
Generally, prior art attempts to control the direction of the fluid discharged from a jet engine, and hence the direction of the reacting thrust, include a nozzle assembly that is mounted in combination with the jet engine exhaust duct. Several thrust-controlling nozzle assemblies are known in the art, for example, U.S. Pat. No. 3,774,868, issued to G. F. Goetz; U.S. Pat. No. 3,570,247, issued to Denning et al.; and, U.S. Pat. No. 3,276,696 issued to B. K. Brandt. Each of these prior art attempts includes structure for dividing the exhausted fluid stream into two separate flow streams and in each case, directional control is obtained by the use of control panels or vanes that can be positioned to extend into each flow stream to deflect each flow stream away from the normal axial thrust direction.
In the structure disclosed by Goetz and Denning et al., the control panels form a portion of a nozzle centerbody that bifurcates the fluid flowing from the jet engine into the two separate flow streams. In the Brandt patent, the control panels are externally mounted aft of and between two adjacent exit orifices of a jet nozzle. In each of the references, the control panels are deployable to angularly deflect the two fluid streams that are exhausted from the nozzle away from one another to control the direction of thrust.
One drawback of the above prior art structure is that thrust vectoring is obtained by deflecting one of the two flow streams while the second flow stream is not deflected. Thus, only a limited upward or downward thrust component can be established. Secondly, rather complex actuation mechanism is required to deploy the deflection control panels. In addition, with respect to nozzles in which the control panels form a portion of the surface of the centerbody, the deflection control panels must be precisely dimensioned so as to form an aerodynamically smooth surface when the panels are retracted.
Accordingly, it is an object of this invention to provide a jet engine nozzle with directional control over the exited flow stream for thrust reversal, thrust spoilage and thrust vectoring.
It is yet another object of this invention to provide a jet engine nozzle in which the entire exited flow stream can be angularly deflected to supply improved thrust vectoring capability.
It is still another object of this invention to provide a jet engine nozzle that includes deflection control panels that can be deployed by relatively simple mechanical means.